A substantial variety of snap-in type fasteners have been developed in the past for securing a threaded member to an article such as a plate or panel or the like. A considerably lesser number of snap-in type fasteners have been developed which additionally are provided with torque arms that prevent loosening of the threaded member after the fastener has been inserted into the article opening and the threaded member has been secured to the fastener.
An example of a friction nut that is provided with torque arms for applying a force resisting loosening of the threaded member from the nut is disclosed in U.S. Pat. No. 2,560,518, the disclosure of which is incorporated herein by reference. The nut, however, is not a snap-in type fastener and is not provided with a self-locking feature initiated by the threaded member.
A constant torque snap-in type fastener is disclosed in U.S. Pat. No. 3,645,311, the disclosure of which is incorporated herein by reference. The force resisting loosening of the threaded member is, however, not in the form of opposed spaced-apart arms but rather a single cantilevered portion of the thread engagement means adapted to engage only one side of the threaded member.
A snap-in type fastener is also disclosed in U.S. Pat. No. 4,300,865, the disclosure of which is incorporated herein by reference. The fastener, although provided with self-locking prongs that penetrate the article as the threaded member is tightened, is not provided with opposed spaced-apart torque arms that are able to press against opposite sides of the threaded member to inhibit its loosening.
Since there are many applications in which vibration might tend to loosen either or both the threaded member and the fastener, a need exists to provide a low cost, snap-in type fastener that is simple to manufacture and provides a self-locking feature in combination with means for applying a force against opposite sides of the threaded member to inhibit its loosening.